JP3718194B2 - Manufacturing method and apparatus for manufacturing rubber sheet containing short fibers - Google Patents

Description

【００４９】
そして、表２に示す環状拡張ダイの拡張比、シリンダーの温度条件によって短繊維混入ゴムを吐出口に向かって徐々に大きくなる円周方向へ引き伸ばして筒状成形体を押出成形した。更に、切断部材としてナイフを、押出された筒状成形体から１８０°対角側の１個所で発生したウェルドラインを中心にして左右に設けた２個所の切断部材を配置し、２個所切開しながらウェルドラインを含むスクラップ片を押出方向に沿って切断除去しながら、一枚のシートにし、これを帆布製ライナーに重ねて個々の巻取ロールに巻付けた。
【００５０】
得られたシートの伸び率格差（Ｅ_１−Ｅ_２）とシートの両端部（サイド）での波打ち、そしてシート厚みのバラツキを求めた。その結果を表２に示す。尚、上記伸び率Ｅ_１、伸び率Ｅ_２の測定では、筒状成形体の切開した直後のサイドの長さ方向とそれ以外のところの長さ方向に沿って間隔１０ｃｍのマークを付け、巻き取る直前における寸法安定したシートのマーク間隔から算出した。
【００５１】
【表２】

【００５２】
これによると、実施例１〜３では、サイドとそれ以外の伸び率格差を適量範囲にすることでシートの波打ち現象を阻止し、かつウェルドラインを含むスクラップ片を切断除去するために、シートの厚みのバラツキが小さいおことが判る。しかし、比較例１では、ウェルドラインを含むスクラップ片を切断除去しないために、サイドの伸び率格差が大きくなって、シートの波打ち現象が発生し、またシートの厚みのバラツキも大きくなっていることが判る。
【００５３】
【発明の効果】
以上のように本願請求項に係る発明では、吐出口へ向かって徐々に径を拡張して円錐形にした内ダイを外ダイに収容し、短繊維混入ゴムを、円周方向へ引き伸ばしながら短繊維を円周方向に配向させた筒状成形体に押出成形し、筒状成形体に発生したウェルドラインを含むスクラップ片を押出方向に沿って切断除去しながら、筒状成形体を一枚シートに巻き取る短繊維入りゴムシートの製造方法と製造装置にあり、サイドの伸長を抑えることができてシートの波打ち現象を阻止し、またウェルドラインを含むスクラップ片を切断除去するために、シートの厚みや短繊維の配向性も均一にすることができ、そしてスクラップ片は未加硫ゴムであり再利用できる効果がある。
【図面の簡単な説明】
【図１】本発明に係る短繊維入りゴム成形体の製造装置の要部概略図である。
【図２】図１の部分断面図である。
【図３】図１をＡ−Ａ方向から見た図である。
【図４】本発明において押出成形した筒状成形体を切開した状態を示す図である。
【図５】従来の方法において押出成形した筒状成形体を切開した状態を示す図である。
【符号の説明】
１ 短繊維入りゴム成形体の製造装置
２ シリンダー
３ 押出スクリュー
６ 押出機
７ 短繊維混入ゴム
９ 内ダイ
１０ 外ダイ
１３ 筒状成形体
１４ ウェルドライン
１５ 環状拡張ダイ
１６ スクラップ片
１８ シート
２０ 切断手段
２１ 切断部材
３０ スクラップ回収手段
３１ 収容箱
４０ 巻き取り手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a rubber sheet containing short fibers and a manufacturing apparatus therefor, and more specifically, a cylindrical shape in which short fibers are oriented in the circumferential direction by an expansion die that gradually increases the short fiber mixed rubber toward the discharge port. While extruding into a molded body and further scraping and removing scrap pieces including a weld line generated in the cylindrical molded body immediately after being extruded along the extrusion direction, the cylindrical molded body is wound around a single sheet to form a sheet. The present invention relates to a method for manufacturing a rubber sheet containing short fibers that prevents undulation and a manufacturing apparatus therefor.
[0002]
[Prior art]
Conventionally, as a method for orienting short fibers in a certain direction in unvulcanized rubber, uncured rubber containing short fibers is put into a pair of calender rolls whose rotation speed is changed in the rolling sheet manufacturing process and rolled. The short fibers in the rubber sheet were oriented in the rolling direction of the sheet and cut according to the belt width to be molded. Thereafter, several rolled sheets cut in the laminating process are overlapped and laminated to a predetermined thickness, and in the winding process, a laminate in which short fibers are oriented in the width direction is wound around a forming drum and used for the manufacture of a transmission belt. It was.
[0003]
That is, in the manufacturing method of the transmission belt of the V-ribbed belt or the low-edge V-belt, one or more cover canvases and an adhesive rubber layer are wound around the circumferential surface of a cylindrical molding drum, and then a cord made of a cord is formed thereon. Was wound in a spiral shape, and further a compressed rubber layer was wound in order to obtain a laminate, which was then vulcanized into a belt sleeve. The compressed rubber layer used here had a thickness of 3 to 4 layers, and was wound around a molding drum with short fibers oriented in the sheet width direction.
[0004]
However, unless the thickness of the rolled sheet is reduced, the short fibers cannot be sufficiently oriented in the sheet rolling direction, and the sheets are unavoidably stacked. Was.
[0005]
As a method for improving this, an extruder equipped with an expansion die is used to orient short fibers in the circumferential direction of the extruded cylindrical body. An expansion space portion is provided in which the flow passage width changes up to the flow passage width of the expansion die. It has been proposed that the channel width of the outlet portion is set to be equal to or smaller than the channel width of the intermediate portion, which is narrower than the channel width. (For example, see Patent Document 1)
[0006]
And there is provided a cutting device for incising the cylindrical elastomer in which the extruded short fibers are oriented in the circumferential direction in the axial direction, a developing device for expanding the incised elastomer into a flat plate shape, and further comprising an extrusion device and a cutting device. A guide device is provided in between, and air is blown from here to cool down while suppressing the shrinkage of the cylindrical elastomer in the circumferential direction, preventing disorder of orientation of short fibers due to uneven shrinkage. Also disclosed is a manufacturing apparatus that prevents the occurrence of flare (waving) by adjusting the inclination of the developing mechanism so that the distance between the both ends and the center of the sheet is equal. (For example, see Patent Document 2)
[0007]
[Patent Document 1]
Japanese Patent Publication No. 6-9847 [Patent Document 2]
JP-A-6-106602 gazette
[Problems to be solved by the invention]
However, in the method using the conventional expansion die, the orientation ratio is adjusted three-dimensionally by controlling the flow width ratio of the inlet space / intermediate space, the intermediate space / exit space, the radius of the inlet / outlet portion, and the cross-sectional area. However, since the orientation rate is controlled by the flow force resulting from the die shape, the orientation rate could not be changed without replacing the die.
[0009]
In addition, when the die is connected to the tip of the cylinder to convert the rubber flow from a horizontal direction to a right angle direction into an extruded crosshead, the die part is arranged in the vertical direction, so internal distortion such as bending is not caused. Since it is small, the dimensional accuracy such as the thickness of the cylindrical extruded product is improved. However, due to the rubber flow path design (flow guide) in the crosshead for uniforming the thickness distribution in the circumferential direction of the cylindrical extruded product, the weld line is usually on the extruder side and the 180 ° diagonal side. From two locations, it occurs at one location 180 ° diagonal from the extruder side. However, the weld line is a collision region of plastically flowing rubber, and is a portion where short fibers are randomly oriented and thin.
[0010]
Therefore, when it is cut on the weld line and wound on one sheet, the side a of the cut surface reaches the roll b while expanding and expanding from the position immediately after the incision as shown in FIG. The area other than is not stretched and reaches the roll b. That is, when H, which is the length between the incision point c on the side a and the roll arrival point d, exceeds a certain value, it is excessively stretched and remains as a permanent distortion, which may occur as a wavy phenomenon when it becomes a sheet. there were.
[0011]
The present invention pays attention to such a problem, and as a result of earnest research, while cutting and removing scrap pieces including a weld line generated in the cylindrical molded body immediately after being extruded along the extrusion direction, one cylindrical molded body is obtained. An object of the present invention is to provide a method for manufacturing a rubber sheet containing short fibers and an apparatus for manufacturing the same, which prevent the sheet from wavy by winding up on the sheet and further uniformize the thickness of the sheet and the orientation of the short fibers.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the present invention is that a short fiber and rubber are kneaded with an extrusion screw of a cylinder and then extruded with an annular expansion die. In the method of manufacturing a rubber sheet containing short fibers that is cut and finished into a sheet,
A cylindrical molded body in which short fibers are oriented in the circumferential direction by an annular expansion die in which an inner die, which has a conical shape by gradually expanding the diameter of the rubber mixed with short fibers toward the discharge port, is housed in the outer die. Extruded,
While cutting and removing scrap pieces including a weld line generated in the cylindrical molded body along the extrusion direction, the cylindrical molded body is wound around one sheet.
It exists in the manufacturing method of the rubber sheet containing a short fiber.
[0013]
In this manufacturing method, while scrap pieces including weld lines generated in the cylindrical molded body are cut and removed along the extrusion direction, the cylindrical molded body is wound around a single sheet, and the side elongation is suppressed. Prevents undulation phenomenon, cuts and removes scrap pieces including weld lines, makes sheet thickness and orientation of short fibers uniform, and enables reuse of unvulcanized rubber scrap pieces .
[0014]
Invention of Claim 2 of this application exists in the manufacturing method of the rubber sheet containing a short fiber which cut | disconnects along the extrusion direction in the left-right position centering on the weld line, and removes the generated scrap piece.
[0015]
Invention of Claim 3 of this application exists in the manufacturing method of the rubber sheet containing a short fiber whose arc length of a scrap piece is 5-25, when the outer periphery length of the cylindrical molded object immediately after extrusion is set to 100. FIG.
[0016]
In the invention according to claim 4 of the present invention, when the elongation rate in the length direction of the side of the cut cylindrical molded body is set to E ₁ and the elongation rate E ₂ in the same length direction other than the side, the elongation rate difference _(E 1 -E ₂₎ is in the short fiber-filled method of manufacturing a rubber sheet is 0-5.
[0017]
The invention according to claim 5 of the present application resides in a method for producing a rubber sheet containing short fibers in which a rubber flow is converted from a horizontal direction to a vertical direction and a cylindrical molded body is extruded in a direction against gravity. The shaped molded body is not deformed by gravity and can be extruded in a state with little dimensional change.
[0018]
The invention according to claim 6 of the present application is a method for producing a rubber sheet containing short fibers which applies a tension in the circumferential direction while blowing cold air or compressed gas inside the cylindrical molded body when the cylindrical molded body is opened. Can be made into a sheet.
[0019]
In the invention according to claim 7 of the present invention, short fibers and rubber are kneaded with an extrusion screw of a cylinder, then extruded by an annular expansion die, and the obtained short fiber-filled rubber cylindrical molded body is cut and finished into a sheet. In the production equipment for rubber sheet with fiber,
A cylinder for kneading rubber containing short fibers by rotation of an extrusion screw;
An annular expansion in which an inner die connected to the cylinder is accommodated in an outer die, the diameter of the inner die is gradually expanded toward the discharge port, and a short fiber is extruded into a cylindrical molded body oriented in the circumferential direction. Die,
A cutting member is disposed at two positions across a weld line that generates a cylindrical molded body immediately after being extruded, and a scrap piece that is cut in the extrusion direction and cutting means that cuts the two places simultaneously to form a single sheet. Scrap recovery means for recovering,
Winding means for individually winding the one sheet,
In the manufacturing apparatus of the rubber sheet containing a short fiber provided with.
[0020]
In this apparatus, the sheet elongation and the orientation of the short fibers can be suppressed in order to suppress the sheet waviness phenomenon and to cut and remove scrap pieces including the weld line. Can also be made uniform. And the scrap piece of unvulcanized rubber can be reused.
[0021]
Invention of Claim 8 of this application manufactures the rubber sheet with a short fiber which has arrange | positioned the cyclic | annular expansion die so that the flow of rubber may be changed from a horizontal direction to a vertical direction, and a cylindrical molded object may be extruded in the direction which resists gravity. In the apparatus, the cylindrical molded body is not deformed by gravity and can be extruded in a state with little dimensional change.
[0022]
Invention of Claim 9 of this application exists in the manufacturing apparatus of the rubber sheet containing a short fiber which provided the gas spraying device which gives tension | tensile_strength in the circumferential direction, spraying cold wind or compressed gas inside the cylindrical molded object immediately after extrusion. Incision can be easily made into a sheet.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, FIG. 1 is a schematic diagram of a main part of an apparatus for producing a rubber molded body containing short fibers according to the present invention, FIG. 2 is a partial sectional view of FIG. 1, and FIG. 3 is a view of FIG. is there.
In the apparatus 1 for producing a short fiber-containing rubber molding of the present invention, as shown in FIGS. 1 and 2, a cylinder 2 for kneading rubber containing short fibers by rotation of an extrusion screw 3 and a short fiber-containing rubber 7 are provided as follows. It has an extruder 6 composed of a connecting pipe 4 to be moved to the process, and the short fiber mixed rubber 7 extruded from the extruder 6 is passed through the gap between the inner die 9 and the outer die 10 toward the discharge port 11. An annular expansion die 15 for extruding a cylindrical molded body 13 in which short fibers are oriented in the circumferential direction by applying gradually increasing circumferential extension, and a cylindrical molded body 13 immediately after being extruded. Two cutting members 21 provided on the left and right sides of the weld line 14 generated at one position 180 ° diagonal from the extruder side are arranged, and the scrap piece 16 including the weld line 14 is cut while cutting two places. While cutting and removing along the extrusion direction It includes a cutting means 20 for the one sheet 18, a scrap collecting means 30 for collecting the scrap pieces 16 incised in the extrusion direction, and a winding means 40 for winding the single sheet 18.
[0024]
As shown in FIG. 2, the cylinder 2 of the extruder 6 accommodates the extrusion screw 3 in a rotatable manner. A rubber compound containing short fibers is inserted from the raw material inlet 17 and is rotated by the rotation of the extrusion screw 3. Fibers and rubber are kneaded to make short fiber-mixed rubber 7. At this time, gas or the like generated from the air in the cylinder 2 or the rubber compound is discharged from an exhaust port (not shown). Although the temperature of the cylinder 2 is changed according to the rubber type, it is usually adjusted to 40 to 100 ° C., and the short fibers and the rubber are heated to a temperature at which they are easily mixed to be thermoplasticized to be easily extruded. In this case, the kneading time is adjusted so that the rubber vulcanization does not proceed. The connecting pipe 4 guides the short fiber mixed rubber 7 to the annular expansion die 15.
[0025]
As shown in FIG. 2, the annular expansion die 15 accommodates an inner die 9 having a conical shape whose diameter is gradually expanded toward the discharge port 11 in an outer die 10. A gap having a predetermined thickness is provided. The short fiber-mixed rubber 7 is extruded into a cylindrical molded body 13 in which short fibers are oriented in the circumferential direction while being gradually stretched in the circumferential direction toward the discharge port 11.
[0026]
Since the annular expansion die 15 is fixed vertically to the horizontally disposed extruder 6 and the cylindrical molded body 13 extruded from the discharge port 11 is placed against the gravity, the cylindrical molded body 13 is placed. Is not deformed by gravity and is extruded with little dimensional change. Further, the annular expansion die 15 arranged in the vertical direction is difficult to bend due to its own weight of the inner die 9, and the gap between the inner die 9 and the outer die 10 is kept constant, whereby the cylindrical molded body 13 having a small thickness deformation amount is formed. Can be finished.
[0027]
The flow path width (nipple) of the inner die 9 and the outer die 10 is uniform from the root portion 19 where the inner die 9 is connected to the extruder 6 to the discharge port 11, and the extrusion of the tubular molded body 13 is braked. Smoothly flow in the longitudinal direction D, and finish into a cylindrical molded body 13 having a uniform thickness without internal distortion.
[0028]
The inner die 9 has a shape in which the diameter gradually increases from the root portion 19 toward the discharge port 11, and the taper angle θ is 30 ° ≦ θ <90 °. The rubber channel inlet diameter is 20 to 120 mm, the rubber channel outlet diameter is 100 to 440 mm, and the expansion ratio (rubber channel outlet diameter / rubber channel inlet diameter) is set to 1.5 to 12.5. Is done. If it is less than this set range, the stretching in the circumferential direction in the vicinity of the discharge port 11 of the inner die 9 is small, and the short fibers are less likely to be oriented in the circumferential direction in the inner and outer layers of the thick cylindrical molded body 13. On the other hand, if the set range is exceeded, the stretching in the circumferential direction becomes too large, and if the extrusion pressure is inferior, the tubular molded body 13 is easily torn.
[0029]
In order to suppress internal heat generation of the short fiber mixed rubber 7 between the inner die 9 and the outer die 10, a cooling device (not shown) in which cooling water is circulated inside the inner die 9 can also be provided. In the cooling device, cooling water is introduced from the outside of the inner die 9, is passed through a passage provided in the inner die 9 by a pump, is discharged from the inner die 9 and is circulated.
[0030]
In the cutting means 20, the cylindrical molded body 13 immediately after the pair of cutting members 21 are extruded is provided at two left and right sides around one weld line 14, and the scrap pieces 16 are continuously arranged along the extrusion direction. To remove. The distance between the pair of cutting members 21 can be adjusted.
[0031]
The weld line 14 is a connecting portion between the extruder 6 arranged in the horizontal direction and the annular expansion die 15 arranged in the direction perpendicular to the extruder 6, and the short fiber-mixed rubber 7 converts from the horizontal direction to the vertical direction. Appears linearly along the extrusion direction at a position 180 ° diagonal to the entrance to the annular expansion die 15. This line is an area where rubber mixed with short fibers in plastic flow collides in the clockwise and counterclockwise direction, or an area where it is difficult to flow, the short fibers are randomly oriented, and the thickness is thinner than other areas, so that the quality This is a problem area.
[0032]
The scrap pieces 16 are unvulcanized rubber having a predetermined width continuous in the extrusion direction, and can be recovered in the storage box 31 of the scrap recovery means 30 and reused.
[0033]
The scrap piece 16 becomes a collision area of rubber during plastic flow, short fibers are randomly oriented, and the thickness thereof is formed thinner than other areas, and the features of the weld line remain. The arc length of the scrap piece 16 is 5 to 25, preferably 10 to 25, assuming that the outer peripheral length of the tubular molded body 13 immediately after extrusion is 100. If the feature remains and exceeds 25, the width of the scrap piece 16 is increased, the effective sheet width is decreased, and scrap is generated more than necessary.
[0034]
Further, as shown in FIG. 4, when the elongation percentage (%) E ₁ in the length direction of the side 25 of the cylindrical molded body 13 is set to the elongation percentage (%) E _{2 in} the length direction other than the side 25, The elongation difference (E ₁ -E ₂ ) is in the range of 0 to 5, and the waviness of the sheet does not occur within this range. When the elongation difference exceeds 5, the elongation of the side 25 increases, and the elongation difference from other than the side 25 increases, and when the sheet is formed, undulations occur on both sides.
[0035]
In the measurement of the elongation rate E ₁ and the elongation rate E ₂ , marks having an interval of 10 cm along the length direction of the side 25 immediately after the incision of the tubular molded body 13 and the length direction of the other side (the original interval) L), and the mark interval of the dimensionally stable sheet 18 at the arrival point of the guide roll 41 (the interval X in the length direction of the side 25, the interval Y in the other length direction) is measured. The elongation in the length direction is obtained by dividing (XL) by L, and the elongation in the other direction in the length direction is obtained by dividing (YL) by L.
[0036]
The cutting member 21 is composed of a cutter such as a cutter or a knife, a laser knife, or a cutter with ultrasonic vibration. The cutting member 21 is cut so as to tear the tubular molded body 13 and finished into one sheet 18 having a predetermined width. Of course, if the cutting member 21 such as a blade is heated and kept warm, incision of the tubular molded body 13 can be facilitated.
[0037]
Moreover, as shown in FIG.1 and FIG.3, the gas spraying apparatus 35 which discharges | emits cold wind or compressed air is provided so that the cylindrical molded object 13 just after extrusion may be given the tension | tensile_strength to the circumferential direction, and it may make it easy to incise. Specifically, the tubular molded body 13 immediately after being extruded is expanded and pulled in the circumferential direction, and at the same time, the tubular molded body 13 is cooled early. This gas spraying device 35 is arranged inside the cylindrical molded body 13 and comprises a compressor (not shown) for supplying compressed air, and a nozzle connected to this and installed in the cylindrical molded body 13, Compressed air is discharged from the nozzles in multiple directions to expand the tubular molded body 13 and apply tension in the circumferential direction, thereby facilitating the incision operation and cooling early to prevent rubber scorching. Stabilize quality.
[0038]
The take-up means 40 winds the cut one sheet 18 individually on the take-up roll 43 by way of the guide roll 41 and over the liner 42.
[0039]
The rubber used here is natural rubber, butyl rubber, styrene-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, alkylated chlorosulfanated polyethylene, hydrogenated nitrile rubber, hydrogenated nitrile rubber and unsaturated carboxylic acid metal salt. Or a rubber material such as ethylene-α-olefin elastomer made of ethylene-propylene rubber (EPR) or ethylene-propylene-diene monomer (EPDM), or a mixture thereof. Examples of diene monomers include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene, and the like.
[0040]
The rubber is made of fibers such as aramid fiber, polyamide fiber, polyester fiber, and cotton, and the length of the fiber varies depending on the type of the fiber, but short fibers of about 1 to 10 mm are used. For example, the aramid fiber is 3 About 5 mm, polyamide fiber, polyester fiber, and cotton are about 5-10 mm. The amount of addition is 10 to 40 parts by weight with respect to 100 parts by weight of rubber.
[0041]
Furthermore, a softener, a reinforcing agent composed of carbon black, a filler, an antiaging agent, a vulcanization accelerator, a vulcanizing agent, and the like are added to the rubber of the present invention.
[0042]
Examples of the softener include general plasticizers for rubber, such as phthalates such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP), adipates such as dioctyl adipate (DOA), and dioctyl sebacate (DOS). Sebacates, phosphates such as tricresyl phosphate, etc., or general petroleum softeners are included.
[0043]
In the present invention, a master batch is prepared by roughening at least rubber short fibers in advance by an open roll, a kneader or the like. In this method, after 10 to 40 parts by weight of short fibers are put into 100 parts by weight of the polymer by an open roll and kneaded, the kneaded master batch is once discharged and cooled to 20 to 50 ° C. This is to prevent rubber scorching.
[0044]
In addition, 1-10 weight part softener can be thrown in with a short fiber. This improves the familiarity between the short fibers and the rubber and improves the dispersion in the rubber, and also has the effect of preventing the short fibers themselves from becoming entangled and becoming cottony. In other words, the softener penetrates into the short fibers and acts as a lubricant to loosen the entanglement between the elementary fibers, prevents the short fibers from becoming cottony, and the familiarity between the short fibers and the rubber. Improves short fiber dispersion. [0045]
Subsequently, rubber containing short fibers is kneaded with the extrusion screw 3 of the cylinder 2 and then extruded from the annular expansion die 15 connected to the tip of the cylinder 2 in the vertical direction to produce the cylindrical molded body 13. The die 9 is accommodated in the outer die 10 to provide a predetermined interval (nipple), and the short fiber-mixed rubber 7 is stretched toward the discharge port 11 in a gradually increasing circumferential direction to orient the short fibers in the circumferential direction. The cylindrical molded body 13 is extruded.
[0046]
After that, the cylindrical molded body 13 continuously extruded is one having a thickness of 1 to 10 mm in which short fibers are uniformly oriented in the circumferential direction from the inner layer to the outer layer, and the cylindrical molded body is taken from the extruder side. Two cutting members 21 provided on the left and right are arranged around the weld line 14 generated at one place on the 180 ° diagonal side, and the scrap piece 16 including the weld line 14 is cut in the extrusion direction while cutting two places. While cutting and removing, a single sheet 18 is formed and the sheet 18 is individually wound. This can be wound around the peripheral surface of the molding drum in the next step and then used for molding the transmission belt.
[0047]
【Example】
Next, specific examples of the method for producing a short fiber-containing rubber molded body are shown below.
Examples 1-3, Comparative Example 1
Using the EPDM rubber compound shown in Table 1, short fibers are previously introduced into the rubber by an open roll and kneaded, and then the kneaded master batch is discharged once and cooled to room temperature. The masterbatch and other compounding agents were put into a cylinder of a short fiber-containing rubber molding shown in FIG. 1, and the short fibers were mixed by rotating the extrusion screw.
[0048]
[Table 1]

[0049]
Then, depending on the expansion ratio of the annular expansion die shown in Table 2 and the temperature condition of the cylinder, the short fiber-mixed rubber was stretched in the circumferential direction gradually increasing toward the discharge port, and a cylindrical molded body was extruded. Further, a knife is arranged as a cutting member, and two cutting members provided on the left and right are arranged around a weld line generated at one location 180 ° diagonally from the extruded cylindrical molded body, and two incisions are made. While the scrap pieces including the weld line were cut and removed along the extrusion direction, they were made into a single sheet, and this was layered on a canvas liner and wound on individual winding rolls.
[0050]
The elongation difference (E ₁ -E ₂ ) of the obtained sheet, undulations at both ends (sides) of the sheet, and variations in sheet thickness were determined. The results are shown in Table 2. In the measurement of the elongation rate E ₁ and the elongation rate E ₂ , marks with a distance of 10 cm are attached along the length direction of the side immediately after the incision of the cylindrical molded body and the length direction of the other portion. It was calculated from the mark interval of the dimensionally stable sheet immediately before taking.
[0051]
[Table 2]

[0052]
According to this, in Examples 1 to 3, in order to prevent the wavy phenomenon of the sheet by making the difference in elongation between the side and the other range within an appropriate range, and to cut and remove the scrap pieces including the weld line, It can be seen that the thickness variation is small. However, in Comparative Example 1, because the scrap pieces including the weld line are not cut and removed, the side elongation rate difference is increased, the sheet waviness phenomenon occurs, and the sheet thickness variation is also increased. I understand.
[0053]
【The invention's effect】
As described above, in the invention according to the claims of the present application, the inner die that is gradually expanded in diameter toward the discharge port and accommodated in the outer die is accommodated in the outer die, and the short fiber mixed rubber is shortened while being stretched in the circumferential direction. Extrude the fiber into a cylindrical shaped body oriented in the circumferential direction, and cut and remove the scrap pieces including the weld line generated in the cylindrical shaped body along the extrusion direction, while taking the single sheet of the cylindrical shaped body In the manufacturing method and the manufacturing apparatus of short fiber rubber sheet wound up on the sheet, it is possible to suppress the side stretching and prevent the sheet wavy phenomenon, and to cut and remove scrap pieces including the weld line, The thickness and the orientation of the short fibers can be made uniform, and the scrap pieces are unvulcanized rubber and have the effect of being reusable.
[Brief description of the drawings]
FIG. 1 is a schematic view of a main part of an apparatus for producing a rubber molded body containing short fibers according to the present invention.
FIG. 2 is a partial cross-sectional view of FIG.
FIG. 3 is a diagram when FIG. 1 is viewed from the direction AA.
FIG. 4 is a view showing a state in which a cylindrical molded body extruded by the present invention is cut open.
FIG. 5 is a view showing a state where a cylindrical molded body extruded by a conventional method is cut open.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus of short fiber containing rubber molding 2 Cylinder 3 Extrusion screw 6 Extruder 7 Short fiber mixing rubber 9 Inner die 10 Outer die 13 Tubular molding 14 Weld line 15 Annular expansion die 16 Scrap piece 18 Sheet 20 Cutting means 21 Cutting member 30 Scrap collecting means 31 Storage box 40 Winding means

Claims (9)

After kneading short fibers and rubber with an extrusion screw of a cylinder, extruding with an annular expansion die, incising a cylindrical molded body of the obtained short fiber containing rubber and finishing it into a sheet,
A cylindrical molded body in which short fibers are oriented in the circumferential direction by an annular expansion die in which an inner die, which has a conical shape by gradually expanding the diameter of the rubber mixed with short fibers toward the discharge port, is housed in the outer die. Extruded,
While cutting and removing scrap pieces including a weld line generated in the cylindrical molded body along the extrusion direction, the cylindrical molded body is wound around one sheet.
The manufacturing method of the rubber sheet containing a short fiber characterized by the above-mentioned. The method for producing a rubber sheet containing short fibers according to claim 1, wherein the scrap pieces generated by cutting along the extrusion direction at left and right positions centering on the weld line are removed. The method for producing a rubber sheet containing short fibers according to claim 1 or 2, wherein the arc length of the scrap pieces is 5 to 25 when the outer peripheral length of the cylindrical molded body immediately after extrusion is 100. When the elongation rate in the length direction of the side of the cut cylindrical molded body is set to E ₁ and the elongation rate E ₂ in the same length direction other than the side, the elongation rate difference (E ₁ −E ₂ ) is 0. It is -5. The manufacturing method of the rubber sheet containing a short fiber in any one of Claims 1-3. The method for producing a rubber sheet containing short fibers according to claim 1, wherein the rubber flow is converted from a horizontal direction to a vertical direction, and the cylindrical molded body is extruded in a direction against gravity. The method for producing a rubber sheet containing short fibers according to any one of claims 1 to 5, wherein when cutting the cylindrical molded body, tension is applied in a circumferential direction while blowing cold air or compressed gas into the cylindrical molded body. After kneading short fibers and rubber with an extrusion screw of a cylinder, extruding with an annular expansion die, incising a cylindrical molded body of the obtained short fiber containing rubber and finishing it into a sheet,
A cylinder for kneading rubber containing short fibers by rotation of an extrusion screw;
An annular expansion in which an inner die connected to the cylinder is accommodated in an outer die, the diameter of the inner die is gradually expanded toward the discharge port, and a short fiber is extruded into a cylindrical molded body oriented in the circumferential direction. Die,
A cutting member is disposed at two positions across a weld line that generates a cylindrical molded body immediately after being extruded, and a scrap piece that is cut in the extrusion direction and cutting means that cuts the two places simultaneously to form a single sheet. Scrap recovery means for recovering,
Winding means for individually winding the one sheet,
An apparatus for producing a rubber sheet containing short fibers. 9. The apparatus for producing a rubber sheet containing short fibers according to claim 8, wherein an annular expansion die is disposed so as to convert a rubber flow from a horizontal direction to a vertical direction and to extrude the cylindrical molded body in a direction against gravity. The manufacturing apparatus of the rubber sheet containing a short fiber of Claim 7 or 8 which provided the gas spraying apparatus which gives tension | tensile_strength in the circumferential direction, spraying cold wind or compressed gas inside the cylindrical molded object immediately after extruded.

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